JP3460443B2 - Maximum injection quantity control device for turbocharged diesel engine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a maximum injection amount control device for a diesel engine, and more particularly to a maximum injection amount control device for a supercharged diesel engine.

[0002]

2. Description of the Related Art Generally, in a diesel engine, an electronic control unit, which controls the diesel engine based on the engine speed and the accelerator opening (engine load), basically calculates the fuel injection amount. An upper limit value (hereinafter referred to as the maximum injection amount Qfull) corresponding to the engine speed and the intake pressure of the engine is set as the amount.

In the conventional calculation of the maximum injection amount Qfull, the electronic control unit calculates "current engine speed-engine speed before Xms" as a judgment value SNE of the speed at which the engine speed rises. ing.

By the way, in a diesel engine with a supercharger,
When the determination value SNE is equal to or higher than the predetermined engine speed, the intake air amount decreases and the smoke is severe because the rise of the boost pressure is delayed even though the engine speed increases quickly. Becomes

Therefore, the electronic control unit determines this judgment value SNE.
Is equal to or higher than the predetermined engine speed, the maximum injection amount Q
Intake pressure correction injection quantity term QMQ used to calculate full
FP is QFULO1 (Qfull offset term), QFUL
By calculating using B1 (intake pressure correction coefficient),
The maximum injection amount is a value lower than the maximum injection amount Qfull calculated when the determination value SNE is less than the predetermined engine speed.

That is, the intake pressure correction injection quantity term QMQFP
Is calculated by the following function (1) when the determination value SNE is less than the predetermined rotation speed, and by the following function (2) when the determination value SNE is greater than or equal to the predetermined rotation speed.

QMQFP = QFULLB * MQFP + QFULO (1) QMQFP = QFULLB1 * MQFP + QFULO1 (2) Note that MQFP is a Qfull intake pressure correction term, and QFULB and QFULB are intake pressure correction factors, QFULO and QFULO.
LO1 is the Qfull offset term.

The above contents will be described with reference to FIG. FIG. 6 is a diagram showing the relationship between the Qfull intake pressure correction injection amount term (QMQFP) and the boost pressure (intake pressure). In the figure, A is a linear line representing the function (1), and B is a linear line representing the function (2). Further, C is the required injection amount (QMQFP) for actual equal smoke, and is represented by a quadratic curve.

When it is desired to obtain the Qfull intake pressure correction injection quantity term so that the smoke becomes equal to smoke regardless of the supercharging pressure, the required injection quantity on the quadratic curve C with respect to the supercharging pressure. And need to. However, since it is difficult to perform such control in actual control, it is approximated by the function (1) expression or the function (2) expression shown by A and B. That is, the state in which the supercharger does not work sufficiently is detected by the increase speed of the engine speed (the determination value SNE), and when the supercharging pressure is high, the function (1) formula (A in FIG. 6) is selected. However, when the boost pressure is low, the function (2) expression (B in FIG. 6) is selected.

[0010]

However, in the high altitude, the supercharging pressure decreases as the atmospheric pressure decreases, and the injection amount in the low intake pressure region is used in the acceleration state in which the engine rotation speed rises quickly as described above. The period becomes longer. That is, since the maximum injection amount Qfull is low, the engine rotation upstroke becomes worse,
There is a period in which the determination value SNE is equal to or lower than a predetermined rotation speed. For this reason, the maximum injection amount Qfull is often calculated using the function (1) formula that results in a higher injection amount, and as a result, there is a possibility that the maximum injection amount Qfull will be worse than the desired smoke at high altitudes, and the injection amount will be Because of hunting, fluctuations in engine speed are also a concern.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to make the maximum injection amount smaller than necessary when the amount of increase in rotation is large even in a low external pressure such as high altitude. Therefore, the maximum injection amount control device for a diesel engine with a supercharger that prevents the engine rotation increase amount from becoming small, and as a result, the maximum injection amount is used and smoke does not deteriorate, is provided. To provide.

[0012]

In order to achieve the above-mentioned object, the invention of claim 1 is a rotation speed detecting means for detecting an engine speed, an intake pressure detecting means for detecting an intake pressure, an engine speed and Basic injection amount calculation means for calculating a basic injection amount according to engine load, and maximum injection amount calculation means for calculating a maximum injection amount that is the maximum value of the basic injection amount that tends to decrease as the intake pressure decreases. And a maximum injection amount correction unit that corrects the maximum injection amount so that the maximum injection amount decreases as the engine speed increase rate increases, in a supercharged diesel engine, the intake pressure is less than or equal to a predetermined value. The gist of the invention is to provide a prohibiting unit that prohibits the correction of the maximum injection amount by the maximum injection amount correcting unit.

According to a second aspect of the present invention, in the first aspect, the maximum injection amount correction means includes a first maximum injection amount when the engine speed increase rate is less than a predetermined value and a second maximum injection amount when the engine speed increase rate is equal to or more than the predetermined value. The gist is that the prohibition means is provided with a lower limit guard for the second maximum injection amount.

(Operation) According to the invention of claim 1, the engine speed detecting means detects the engine speed, and the intake pressure detecting means detects the intake pressure. The basic injection amount calculation means calculates the basic injection amount according to the engine speed and the engine load. The maximum injection amount calculation means calculates the maximum injection amount that is the maximum value of the basic injection amount that tends to decrease as the intake pressure decreases. or,
The maximum injection amount correction means corrects the maximum injection amount such that the larger the engine speed increase rate, the smaller the maximum injection amount. Then, the prohibiting means prohibits the correction of the maximum injection amount by the maximum injection amount correcting means when the intake pressure is equal to or lower than a predetermined value.

According to the second aspect of the present invention, the maximum injection amount correction means selects the first maximum injection amount when the engine speed increase rate is less than the predetermined value, and the second maximum injection amount when the engine speed increase rate is greater than the predetermined value. Select the amount. Then, the prohibiting means provides a lower limit guard for the second maximum injection amount.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a maximum injection amount control device for a diesel engine with a supercharger for a vehicle will be described below with reference to FIGS.

FIG. 1 shows a diesel engine 2 with a supercharger,
FIG. 1 is a schematic configuration diagram showing a distributed fuel injection pump 1 that injects fuel into the diesel engine 2 and a maximum injection amount control device that controls the fuel injection pump 1 to adjust the maximum fuel injection amount to the diesel engine 2. is there.

As shown in FIG. 1, the fuel injection pump 1 has a drive pulley 3 drivingly connected to a crankshaft 40 of a diesel engine 2 via a belt or the like. The fuel injection pump 1 is rotated by the rotation of the drive pulley 3.
Is driven, and fuel is pressure-fed to the fuel injection nozzle 4 provided for each cylinder of the diesel engine 2 to inject fuel.

As shown in FIG. 1, a drive shaft 5 is connected to the drive pulley 3. A fuel feed pump (developed by 90 degrees in the figure) 6 which is a vane type pump and a disc-shaped pulsar 7 having a plurality of protrusions on its outer peripheral surface are attached to the drive shaft 5.

The base end portion (right end portion in the drawing) of the drive shaft 5 is connected to the cam plate 8 via a coupling (not shown). A roller ring 9 is interposed between the pulsar 7 and the cam plate 8, and a plurality of cam rollers 10 facing the cam face 8a of the cam plate 8 are attached to the roller ring 9. The cam plate 8 is constantly driven by the spring 11 so that the cam roller 1
Biased to zero.

A plunger 12 for fuel pressurization is integrally rotatably attached to the cam plate 8, and the rotational force of the drive shaft 5 is transmitted to the cam plate 8 via a coupling, whereby the cam plate 8 is rotated. 8 and the plunger 12 are reciprocally driven in the horizontal direction in the figure while rotating. The plunger 12 is fitted into a cylinder 14 formed in the pump housing 13, and the plunger 12
A high-pressure chamber 15 is formed between the front end surface (right end surface in the figure) of the cylinder and the inner bottom surface of the cylinder 14. The same number of intake grooves 16 and distribution ports 17 as the number of cylinders of the diesel engine 2 are formed on the outer periphery of the plunger 12 on the front end side. A distribution passage 18 and a suction port 19 are formed in the pump housing 13 so as to correspond to the suction groove 16 and the distribution port 17.

When the fuel feed pump 6 is driven based on the rotation of the drive shaft 5, fuel from a fuel tank (not shown) is supplied into the fuel chamber 21 through the fuel supply port 20. Further, in the intake stroke in which the plunger 12 moves (returns) to the left in the drawing and the high pressure chamber 15 is decompressed, one of the intake grooves 16 communicates with the intake port 19 and the fuel chamber 21 to the high pressure chamber 15 is communicated. Fuel is introduced into. On the other hand, the plunger 12 moves to the right in the figure (forward movement).
Then, in the compression stroke in which the high pressure chamber 15 is pressurized, fuel is pressure-fed from the distribution passage 18 to the fuel injection nozzle 4 of each cylinder and injected.

In the pump housing 13, a spill passage 22 for fuel overflow that connects the high pressure chamber 15 and the fuel chamber 21 to each other.
Is formed, and an electromagnetic spill valve 23 as an actuator is provided in the middle thereof. The electromagnetic spill valve 23 is a normally open type valve, and when the coil 24 is not energized (OFF), the valve body 25 is opened and the fuel in the high pressure chamber 15 overflows into the fuel chamber 21. When the coil 24 is energized (turned on), the valve body 25 is closed and the overflow of fuel from the high pressure chamber 15 to the fuel chamber 21 is stopped.

Therefore, by controlling the energization time of the electromagnetic spill valve 23, the electromagnetic spill valve 23 is controlled to be closed / opened, and the overflow amount of fuel from the high pressure chamber 15 to the fuel chamber 21 is adjusted. Then, by opening the electromagnetic spill valve 23 during the compression stroke of the plunger 12, the fuel inside the high pressure chamber 15 is depressurized and the fuel injection from the fuel injection nozzle 4 is stopped. In other words, even if the plunger 12 moves forward, the high pressure chamber 15 remains open while the electromagnetic spill valve 23 is open.
The internal fuel pressure does not rise, and fuel injection from the fuel injection nozzle 4 is not performed. Also, during the forward movement of the plunger 12,
By controlling the timing of closing and opening the electromagnetic spill valve 23, the fuel injection amount from the fuel injection nozzle 4 is controlled.

Below the pump housing 13, a timer device (90 degrees expanded in the figure) 26 for controlling fuel injection timing is provided. The timer device 26 as a timer controls the position of the roller ring 9 with respect to the rotation direction of the drive shaft 5 to thereby cause the cam face 8 to move.
The timing a is engaged with the cam roller 10, that is, the reciprocating timing of the cam plate 8 and the plunger 12 is controlled.

The timer device 26 is operated by hydraulic pressure, and includes a timer housing 27, a timer piston 28 fitted in the timer housing 27, and a low pressure chamber 29 on one side of the timer housing 27. The timer piston 28 is composed of a timer spring 31 and the like that presses and urges the timer piston 28 to the pressure chamber 30 on the other side. The timer piston 28 is connected to the roller ring 9 via a slide pin 32.

In the pressurizing chamber 30 of the timer housing 27,
The fuel pressurized by the fuel feed pump 6 is introduced. The position of the timer piston 28 is determined by the equilibrium relationship between the fuel pressure and the urging force of the timer spring 31. According to this, the position of the roller ring 9 is determined, and the reciprocating timing of the plunger 12 is determined via the cam plate 8.

In order to control the fuel pressure of the timer device 26, a timing control valve (T) as a timer control valve is provided in a communication passage 34 connecting the pressurizing chamber 30 and the low pressure chamber 29.
CV) 33 is provided. The TCV 33 is an electromagnetic valve that is opened / closed by a duty-controlled energization signal, and the fuel pressure in the pressurizing chamber 30 is adjusted by the opening / closing control of the TCV 33. Then, the lift timing of the plunger 12 is controlled by the fuel pressure adjustment, and the fuel injection timing from each fuel injection nozzle 4 is adjusted.

A rotation speed sensor 35, which constitutes a part of the rotation speed detecting means and the operation state detecting means, is attached to the upper portion of the roller ring 9 so as to face the outer peripheral surface of the pulsar 7. The rotation speed sensor 35 is composed of an electromagnetic pickup coil, and outputs a detection signal each time a protrusion formed on the outer peripheral surface of the pulsar 7 crosses. Then, the rotation speed of the fuel injection pump 1, that is, the rotation speed of the crankshaft 40 in the diesel engine 2 is detected from this detection signal.

Next, the diesel engine 2 will be described. As shown in FIG. 1, in this diesel engine 2, a cylinder 41, a piston 42, and a cylinder head 43.
A main combustion chamber 44 is formed for each cylinder, and a sub combustion chamber 45 is connected to each main combustion chamber 44. Then, the fuel injected from each fuel injection nozzle 4 is supplied to each auxiliary combustion chamber 45. Further, a glow plug 46 as a starting assist device is attached to each sub-combustion chamber 45.

In this diesel engine 2, a series of operations consisting of intake, compression, explosion and exhaust is performed by the piston 4.
It is performed in four strokes of 2, that is, two rotations of the crankshaft 40.

An intake pipe 47 and an exhaust pipe 50 are connected to the diesel engine 2, respectively. The intake pipe 47 is provided with a compressor 49 of a turbocharger 48, and the exhaust pipe 50 is provided with a turbine 5 of the turbocharger 48.
1 is provided. A waste gate valve 52 for adjusting the supercharging pressure is attached to the exhaust pipe 50.

The exhaust pipe 50 and the intake pipe 47 are the return pipe 5
4 are connected in a communicating state, and a part of the exhaust gas in the exhaust pipe 50 can be returned to the intake pipe 47. An EGR valve 55 for adjusting the exhaust gas recirculation amount (EGR amount) is provided in the middle of the recirculation pipe 54. This E
The negative pressure applied to the diaphragm chamber of the GR valve 55 is
It is controlled by a vacuum switching valve (VSV) 56.

Further, in the middle of the intake pipe 47, there is provided a throttle valve 58 which is opened / closed in conjunction with an accelerator pedal 57 provided in the driver's seat. A bypass passage 59 is formed in parallel with the throttle valve 58, and a bypass throttle valve 60 is provided in the bypass passage 59 so as to be openable and closable. The bypass throttle valve 60 is opened / closed by an actuator 63. Actuator 63
Is supplied with a negative pressure generated by a negative pressure pump (not shown) via two VSVs 61 and 62.

The electromagnetic spill valve 23, the TCV 33, the glow plug 46, and the VSVs 56, 61, 62 are electrically connected to an electronic control unit (hereinafter simply referred to as "ECU") 71, and their driving timing is the same as that of the ECU 7.
Controlled by 1.

As sensors for detecting the operating state of the diesel engine 2, the following sensors are provided in addition to the rotation speed sensor 35. Intake temperature (intake temperature) of air taken into the intake pipe 47 via the air cleaner 64
An intake air temperature sensor 72 that detects the MQFA, an accelerator opening sensor 73 that detects the accelerator opening ACCP corresponding to the load of the diesel engine 2 from the opening / closing position of the throttle valve 58, and an intake valve that detects the boost pressure VPIM in the intake port 53. An intake pressure sensor 74 as an air pressure detecting means, a water temperature sensor 75 for detecting a cooling water temperature MQFTF of the diesel engine 2, a rotation reference position of the crankshaft 40 of the diesel engine 2, for example, a rotation position of the crankshaft 40 with respect to a top dead center of a specific cylinder. A crank angle sensor 76 for detecting a vehicle speed and a vehicle speed sensor 77 for detecting a traveling speed (vehicle speed) of the vehicle by turning on / off a reed switch 77b by a magnet 77a rotated by rotation of a gear of a transmission (not shown) are provided. There is.

Each of the above-mentioned sensors 3 is provided in the ECU 71.
5, 72 to 77 are respectively connected. And E
The CU 71 suitably controls the electromagnetic spill valve 23, the TCV 33, the glow plug 46, the VSV 56, 61, 62 and the like based on the signals output from the respective sensors 35, 72 to 77.

Next, the configuration of the above-mentioned ECU 71 will be described with reference to the block diagram of FIG. The ECU 71 is a central processing unit (CPU) 81, a read-only memory (RO) in which a predetermined control program, maps and the like are stored in advance.
M) 82, a random access memory (RAM) 83 for temporarily storing the calculation result of the CPU 81, a backup RAM 84 for storing previously stored data, an input port 8
5 and the output port 86 are connected by a bus 87 as a logical operation circuit. Of these, the CPU 81
Constitutes a maximum injection amount calculation means, a maximum injection amount correction means, a basic injection amount calculation means, a prohibition means, a lower limit guard value calculation means, and a maximum injection amount correction means.

The intake temperature sensor 7 is connected to the input port 85.
2, the accelerator opening sensor 73, the intake pressure sensor 74, and the water temperature sensor 75 are connected via the buffers 88, 89, 90, 91, the multiplexer 92, and the A / D converter 93. The input port 85 is provided with the rotation speed sensor 35, the crank angle sensor 76, and the vehicle speed sensor 77.
It is connected through the waveform shaping circuit 95. And C
The PU 81 reads the detection signals of the sensors 35, 72 to 77, etc., which are input via the input port 85, as input values. Further, the output port 86 has drive circuits 96, 97, 9
Electromagnetic spill valve 23 via 8, 99, 100, 101
TCV33, glow plug 46 and VSV56, 61,
62 and the like are connected.

The CPU 81 uses the sensors 35 and 72.
Electromagnetic spill valve 2 based on input values read from ~ 77
3, TCV33, glow plug 46 and VSV56,6
1, 62 and the like are preferably controlled.

Next, the operation and effect of this embodiment configured as described above will be described. FIG. 3 is a fuel injection amount control routine, which is a time interrupt routine executed at predetermined time intervals. When this processing routine is entered, in step 101, the engine speed NE as the engine speed is read from the speed sensor 35, and in step 102
Read the accelerator opening ACCP from the accelerator opening sensor.

In the next step 103, the CPU 8
1 calculates the basic injection amount QB based on the engine speed NE and the accelerator opening ACCP. Step 103 corresponds to the basic injection amount calculation means. Next, at step 104, the maximum injection amount Qfull is calculated. Step 1
Reference numeral 04 corresponds to maximum injection amount calculation means. The maximum injection amount Qfull will be described later. Next, in step 105, the maximum injection amount Qfull and step 1
Qfull ≧ by comparing with the basic injection amount calculated in 03.
If QB, in step 106, the final injection amount Q
If FIN is QB and conversely Qfull <QB,
The final injection amount QFIN is set to Qfull. As a result, in step 107, the energization duty ratio according to the final injection amount is applied to the drive circuit 96 via the output port 86 to operate the electromagnetic spill valve 23, and this processing routine is exited.

Next, the Qfull calculation routine will be described. The flowchart of FIG. 4 shows a Qfull calculation routine executed by the CPU 81 for calculating the maximum injection amount Qfull.

In step 201, the CPU 81 determines the Qfull intake pressure correction coefficient QFULLB based on the engine speed NE.
And the offset term QFULO is calculated with reference to the map stored in the ROM 82. This map is created in advance based on experimental values and the like. Next, in step 202, the supercharging pressure VPIM is read. Subsequently, at step 203, the Qfull intake pressure correction term MQFP is calculated based on the supercharging pressure VPIM by referring to the map stored in the ROM 82.

Next, at step 204, the injection amount lower limit guard value MQMQFP is calculated with reference to the lower limit guard map stored in the ROM 82 based on the engine speed NE. This lower limit guard map is created beforehand based on experimental values and the like. This step 204 constitutes the lower limit guard value calculation means. Next, Step 205
At, the rotation speed up determination flag XNSE is 1
Is set to. This rotation speed up determination flag XNSE is controlled by a main routine different from this processing routine. That is, C
In the main routine, the PU 81 determines “current engine speed−X
"engine speed before ms" is calculated, that is, the engine speed increase rate is calculated, and when this determination value SNE is equal to or higher than a predetermined engine speed increase rate, the rotational speed rising speed determination flag XNSE is set to 1. And if not, reset to 0.

If it is determined in step 205 that the rotational speed-up speed determination flag XNSE is set to 1, it is determined that the current rotational speed-up speed is equal to or higher than the predetermined engine speed, and the routine proceeds to step 206. Step 20
6, the function (2) is expressed as follows: QMQFP = QFULLB1 * MQFP + QFU
LO1 is calculated to determine the magnitude relationship between the calculated QMQFP and the maximum injection amount injection amount lower limit guard value MQMQFP. This injection amount lower limit guard value MQMQFP has been previously obtained by an experimental value or the like, and even when the engine rotation increase rate is large, the maximum injection amount Qfull calculated later will be unnecessarily large even at low ambient pressure such as in highlands. It is a value that does not decrease. The step 206 constitutes a prohibition means.

When the calculated value of the function (2) is equal to or larger than the injection amount lower limit guard value MQMQFP in step 206, the calculated value of the function (2) is Q in step 207.
It is stored in the register as the full intake pressure correction injection amount term QMQFP, and the routine proceeds to step 208. Function (2)
The calculated value of the formula is the second maximum injection amount. When the value of the function (2) is less than the injection amount lower limit guard value MQMQFP in step 206, the injection amount lower limit guard value MQMQF is determined in step 209.
P is stored in the register as the Qfull intake pressure correction injection amount term QMQFP, and the routine proceeds to step 208.

Further, in step 205, when the rotational speed-up determination flag XNSE is not set to 1, that is, the rotational speed-up determination flag X.
Step 2 if NSE is reset to 0
In 10, the function (1) expression, that is, QMQFP = QFULLB * MQFP + QFUL
O 2 is calculated, this calculated value is stored in the register as the Qfull intake pressure correction injection amount term QMQFP, and step 20
Go to 8. The calculated value of the function (1) is the first maximum injection amount.

When the process proceeds from step 207, step 209 or step 210 to step 208, the maximum injection amount Qfull is calculated in step 208 based on the following equation (3).

Qfull = <[MIN (QMQFP * MQFA, QFULJ]> * MQFTF (3) QFULJ is the maximum injection amount correction term upper limit value, which is a value obtained in advance by experiments or the like. Various other conditions such as fuel temperature correction are included in the calculation, but the description thereof is omitted here.

Therefore, in equation (3), QMQFP * MQFA,
Cooling water temperature MQFTF for the smaller of QFULJ
Qfull is calculated by multiplying by. After performing the above calculation, the Qfull calculation routine is exited. (A) Now, according to the maximum injection amount control device for a diesel engine with a supercharger configured as described above, when steps 205 to 208 are performed, the current rotation speed is the predetermined engine speed. This is a case where the rate of increase is equal to or higher than the increase rate, and the calculated value of the function (2) in step 206 is equal to or higher than the injection amount lower limit guard value MQMQFP. Therefore, in this case, the calculation of the maximum injection amount Qfull in step 208 is performed by Qfull corresponding to the straight line portion of B in FIG.
The intake pressure correction injection quantity term QMQFP is used. Note that FIG. 5 is a drawing in which only B of FIG. 6 is taken out. (B) When Step 205, Step 206, Step 209, and Step 208 have been performed, the current rotational speed of rotation is equal to or higher than the predetermined engine rotational speed increase rate, and the calculated value of the function (2) expression in Step 206 is This is the case where the injection amount lower limit guard value is less than MQMQFP. Therefore, in this case, the maximum injection amount Qfull in step 208 is calculated by setting the injection amount lower limit guard value (G portion in the drawing) in FIG. 5 to the Qfull intake pressure correction injection amount term QMQFP.
Used as.

As a result, the injection amount lower limit guard value MQMQF
Since the maximum injection amount Qfull is used by using P, the maximum injection amount becomes unnecessarily small when the engine rotation increase rate is large, even when the atmospheric pressure is low, unlike the conventional case. To avoid. (C) Further, when step 205, step 210, and step 208 have been performed, the current rotational speed of rotation is less than the predetermined engine rotational speed increase rate. Therefore, in this case, the calculation of the maximum injection amount Qfull in step 208 is used as the Qfull intake pressure correction injection amount term QMQFP corresponding to the straight line portion of A in FIG.

Next, a second embodiment will be described with reference to FIG. It is to be noted that the description will be focused on the points different from the above-described embodiment, the same reference numerals as those in the above-mentioned embodiment will be given, and description thereof will be omitted. In this embodiment, only the Qfull calculation routine is different.

That is, in the Qfull calculation routine of the above-mentioned embodiment, step 204 is omitted, and instead of step 206, step 211 as prohibiting means.
However, the process of step 212 is performed instead of step 209. In this embodiment, step 203 constitutes intake pressure correction term calculation means.

Explaining step 211, in step 211, it is determined whether the Qfull intake pressure correction term calculated in step 203 is greater than or equal to the intake pressure correction term lower limit guard value MQFPL. This intake pressure correction term lower limit guard value MQFPL has been obtained in advance from an experimental value, etc., and even when the external pressure is low, such as at high altitudes, when the rotational increase amount is large, the maximum injection amount Qfull calculated later is greater than necessary. It is a value that does not become small.

In step 211, the Qfull intake pressure correction term MQFP is the intake pressure correction term lower limit guard value MQFP.
If it is greater than L, the process proceeds to step 207. Therefore, in step 207, as in the first embodiment, the calculated value of the function (2) is stored in the register as the Qfull intake pressure correction injection amount term QMQFP.

Further, in step 211, Qfull
The intake pressure correction term MQFP is the intake pressure correction term lower limit guard value MQ.
If it is less than FPL, the process proceeds to step 212. In step 212, the Qfull intake pressure correction injection amount term QMQFP is calculated by the following equation and stored in the register,
Control goes to step 109.

QMQFP = QFULL1 * MQFP
L + QFULO1 (d) Now, in the second embodiment configured as described above, step 205, step 211, step 2
If 07 and step 208 have been passed, the current rotational speed of rotation is equal to or higher than the predetermined engine speed increase rate, and step 2
This is the case where the Qfull intake pressure correction term MQFP in 11 is greater than or equal to the intake pressure correction term lower limit guard value MQFPL. Therefore, in this case, the maximum injection amount Q in step 208
For the calculation of full, the Qfull intake pressure correction injection amount term QMQFP corresponding to the straight line portion of B in FIG. 8 is used. Note that FIG. 8 is a drawing in which only B of FIG. 6 is taken out. (E) In addition, when Step 205, Step 211, Step 212, and Step 208 are performed, the current rotational speed of rotation is equal to or higher than the predetermined engine rotation increase rate, and the Qfull intake pressure correction term MQFP in Step 211 is equal to the intake pressure. This is the case where the correction term lower limit guard value is less than MQFPL.
That is, in step 212, the intake pressure correction term lower limit guard value MQFPL is used in place of MQFPL during the calculation of the Qfull intake pressure correction injection quantity term QMQFP, so that substantially the same as in the first embodiment. Figure 8
Becomes the lower limit guard indicated by G1 in
Used as the full intake pressure correction injection quantity term QMQFP.

As a result, the intake pressure correction term lower limit guard MQF
Since the maximum injection amount Qfull is used using PL,
Unlike the conventional case, even if the atmospheric pressure is low such as in highlands, it is possible to prevent the maximum injection amount from becoming unnecessarily small when the rotation increase amount is large. (F) Step 205, Step 210, Step 2
After 08, the current rotational speed of rotation is less than the predetermined engine rotational speed increase rate as in the first embodiment. Therefore, in this case, the calculation of the maximum injection amount Qfull in step 208 is used as the Qfull intake pressure correction injection amount term QMQFP corresponding to the straight line portion of A in FIG. 6 (a) In the above embodiment, the present invention is applied. Is embodied in the diesel engine 2 including the supercharger (turbocharger 48), but may be embodied in a diesel engine including a supercharger as the supercharger. (B) In the above-described embodiment, the function has two types, function (1) and function (2), but the intake pressure correction coefficient is
And Qfull offset terms may be realized among a plurality of different functions such as three types and four types having different Qfull offset terms.

The technical idea understood from the matters described in the above-mentioned embodiment other than the claims described in the claims will be described together with the effects thereof. (1) In claim 1, the maximum injection amount correction means is
An intake pressure correction term calculation means for calculating an intake pressure correction term based on the intake pressure, and a predetermined intake pressure correction term lower limit guard value when the engine speed increase rate is a predetermined value or more, and the intake pressure The diesel engine with a supercharger is for comparing with a correction term, and the prohibiting means selects the lower limit guard value when the intake pressure correction term is smaller than the lower limit guard value. Maximum injection amount control device. With this configuration, since the maximum injection amount Qfull is used by using the intake pressure correction term lower limit guard value MQFPL, unlike the conventional case, even when the external pressure is low, such as in highlands, when the rotation increase amount is large, the maximum It is avoided that the injection amount becomes smaller than necessary.

[0061]

As described above in detail, according to the present invention, even when the atmospheric pressure is low, the maximum injection amount is prevented from becoming unnecessarily small when the rotation increase amount is large. The amount of increase in engine speed does not decrease, and as a result, the maximum injection amount is used and smoke is not deteriorated.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a diesel engine with a supercharger, a fuel injection pump, and a maximum injection amount control device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an electrical configuration of the ECU.

FIG. 3 is a flowchart of a fuel injection amount control routine executed by the ECU.

FIG. 4 is a flowchart of a Qfull calculation routine executed by the ECU.

FIG. 5 is an explanatory diagram showing a relationship between a supercharging pressure and a Qfull intake pressure correction injection amount term.

FIG. 6 is an explanatory diagram showing a relationship between a conventional supercharging pressure and a Qfull intake pressure correction injection amount term.

FIG. 7 is a flowchart of a Qfull calculation routine according to the second embodiment.

FIG. 8 is an explanatory diagram showing the relationship between the supercharging pressure and the Qfull intake pressure correction injection amount term of the second embodiment.

[Explanation of symbols]

2 ... Diesel engine, 35 ... Rotational speed sensor constituting rotational speed detecting means and operating state detecting means, 73 ... Accelerator opening sensor, 81 ... Maximum injection amount calculating means, basic injection amount calculating means, maximum injection amount correcting means , CP constituting the prohibition means, the lower limit guard value calculation means, and the intake pressure correction term calculation means
U, MQFPL ... Intake pressure correction term lower limit guard value.

   ─────────────────────────────────────────────────── ─── Continued front page       (56) Reference JP-A-6-173741 (JP, A)                 JP-A-7-324645 (JP, A)                 JP-A-63-239338 (JP, A)                 JP-A-59-153931 (JP, A)                 JP-A-8-303271 (JP, A)

Claims (2)

(57) [Claims] 1. A rotation speed detecting means for detecting an engine speed, an intake pressure detecting means for detecting an intake pressure, and a basic injection amount calculating means for calculating a basic injection amount according to the engine speed and an engine load. A maximum injection amount calculation means for calculating a maximum injection amount which is the maximum value of the basic injection amount, which tends to become smaller as the intake pressure becomes lower; and the maximum injection amount becomes smaller as the engine speed increase rate increases. In the diesel engine with a supercharger, the maximum injection amount correction unit for correcting the maximum injection amount is provided with a prohibition unit for prohibiting the maximum injection amount correction by the maximum injection amount correction unit when the intake pressure is equal to or lower than a predetermined value. A maximum injection amount control device for a diesel engine with a supercharger. 2. The maximum injection amount control device for a diesel engine with a supercharger according to claim 1, wherein the maximum injection amount correction means has a first maximum injection amount when the engine speed increase rate is less than a predetermined value, A maximum of the diesel engine with a supercharger, comprising selecting the second maximum injection amount when the value is equal to or more than a predetermined value, and the prohibiting means comprising providing a lower limit guard to the second maximum injection amount. Injection amount control device.